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How to Choose a Gage Block Set (36 vs 81 vs 88 vs 112 Piece)
Guide · Updated October 27, 2026
Buying your first gage block set, or one as a gift? Pick the units first, then the number of pieces, then the grade. The size ranges below come from the same solver the free Gage Block Calculator uses, counting each block once per stack.
1. Inch or metric?
Buy the units the drawings use. Converting a metric size to an inch stack works (see the inch-to-mm stack chart), but a set in the native units gives shorter stacks.
2. How many pieces?
| Set | Builds (each block used once) | Good for |
|---|---|---|
| 36-piece inch | 0.3000 to 10.4495 in, 0.0001 in steps | Home shop, apprentice, budget |
| 81-piece inch | 0.2000 to 26.3295 in, 0.0001 in steps | The general-purpose US shop set |
| 28-piece inch (thin) | 0.0400 to 0.8195 in, 0.0001 in steps | Thin stacks, add-on to another set |
| 88-piece metric | 2.000 to 713.295 mm, 0.001 mm steps | The common metric set |
| 112-piece metric | 2.000 to 930.795 mm, 0.001 mm steps | Fewer blocks in mid-size stacks |
Fewer pieces means more blocks per stack for some sizes, and every wrung joint adds a little error. Compare real stacks: 1.2345 in, 2.1875 in, 25.4 mm or all worked stacks.
3. Which grade?
Calibration labs need the tightest grades; most shop-floor and home-shop work is well served by a workshop grade with a current certificate. See gage block grades explained for the ASME and ISO tolerance tables. Still deciding between blocks and a micrometer? See gage block set vs micrometer.
4. Before you buy (or wrap it)
- Check the listing for the grade, material and a calibration certificate.
- Add a deburring stone and rust preventive; see care and wear blocks.
- Learn to wring them: how to wring gage blocks.
Gage block sets to compare
- HFS 36-piece inch gage block set: compact budget inch set. Check the listing for grade and certificate.
- 81-piece inch gage block sets: compare grades and certificates.
- Mitutoyo 516-938-26 112-piece metric set: full metric set listed as Grade 0.
- Gage block accessory sets: holders, jaws and scribers.
Worked example: picking a set for a small shop
A small job shop mostly checks micrometers, calipers, and bore-gage setups in inches, and it doesn't have a temperature-controlled room. An 81-piece inch set covers most stacks with three or four blocks, and the shop has no need for metric blocks often enough to buy a second set. A shop-grade set (ASME Grade 2 or similar) fits that work better than lab grade. Its accuracy is already finer than the tools being checked, and the shop's temperature swings would cancel out the difference anyway. Add a pair of wear blocks so the working faces of the main set don't wear, and budget for periodic calibration. Check the maker's grade certificate before buying, not the listing description.
FAQ
Which gage block set should I buy first?
For most US shops working in inches, the 81-piece inch set. For a home shop on a budget, the 36-piece inch set. For metric work, the 88-piece metric set, or the 112-piece set if you want fewer blocks in mid-size stacks.
What sizes can an 81-piece gage block set make?
Every size in steps of 0.0001 in from 0.2000 to 26.3295 in, using each block only once.
What is the difference between the 88 and 112 piece metric sets?
Both build every 0.001 mm step from 2.000 mm. The 112-piece set extends the 0.5 mm series to 24.5 mm and adds 25, 50, 75 and 100 mm blocks, so mid-size stacks often need fewer blocks and the longest stack reaches 930.795 mm instead of 713.295 mm.
New: How to build a gage block stack: the digit-by-digit method for the fewest blocks. Then build it free in the gage block calculator · worked stacks · carbide vs steel blocks · gage block accessories.
Shopping for a machinist?
See the Machinist Christmas Gift Guide 2026, grouped by budget, then try any set in the free Gage Block Calculator.
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